Nozzle blade lip



y 1962 w. c. NOTBOHM 3,034,578

NOZZLE BLADE LIP Filed Jan. 29, 1959 1294 M,w,-w

ArrOlEWEYf United States Patent .0

3,034,578 NOZZLE BLADE LIP Willard C. Notbohm, Appleton, Wis., assignor to Valley Iron Works Company, Appleton, Wis., a corporation of Wisconsin Filed Jan. 29, 1959, Ser. No. 789,824 7 Claims. (Cl. 162347) This invention relates to a nozzle blade lip for paper making machines.

The lip may be used on any existing slice blade in primary or secondary head box installations such as those illustrated in Niks l,8l8,267 or Boronow 2,782,692, the object being, in either case, to provide a lip fixed to the nozzle blade either as a part thereof or as an attachment, and sufliciently flexible to partake of nozzle blade adjustment throughout each increment of its length, the lip being adapted to improve formation and profile of the paper on the Fourdrinier wire and so shaped that throughout the range of normal adjustment, the reduction in coeflicient of flow through the nozzle will remain approximately constant.

The flexible blade is provided with numerous rods individually adjustable to regulate the nozzle opening so that flow onto the wire can be controlled with accuracy and increased or decreased locally at any desired point throughout the width of the wire. Uniformity in stock composition is desirably promoted by a distributing roll or the like within the head box. The resulting eddy currents mix the stock but tend to decay at or before the nozzle. The lip tends to produce eddy currents of a very minute and controlled nature which maintain the mixture uniform, but streaks will result when the blade is warped if the warping results in a change of pattern of the eddy currents. The lip disclosed avoids streaks under these circumstances because the distribution remains substantially constant, notwithstanding localized variation in nozzle opening.

In the drawings:

FIG. 1 is a fragmentary detail view in cross section through a nozzle equipped with a nozzle blade lip embodyin g the invention.

FIG. 2 is a fragmentary detail view showing the lip formed integrally on the margin of the blade, the blade and lip being illustrated in cross section on a slightly enlarged scale as compared with FIG. 1.

FIG. 3 is an enlarged fiagmentary detail view of a modified embodiment shown in cross section on the line 3-3 of FIG. 4 through a separately fabricated lip and a fragment of the nozzle blade.

FIG. 4 is a fragmentary front elevational view on reduced scale of the structure of FIG. 3.

The nozzle 5 discharges stock from the head box 6 onto the Fourdrinier wire 11 or other foraminous support upon which the paper is to be laid. The stock has desirably been homogenized by passage over the usual distributing roll 12.

In accordance with conventional practice, the front wall of the head box may comprise a vertically adjustable gate 7 to which is pivot-ally connected the rear mar-gin of a flerdble nozzle blade or slice blade 8 constituting the top wall of a stock discharge nozzle. The nozzle blade converges toward the front margin of the nozzle apron 9 over which the stock flows to the point of discharge. It is common practice, illustrated in the above mentioned patents, to provide adjustable supports for the nozzle blade 8 at intervals along its free margin, such supports being represented by the rods 10.

The present invention is not concerned with the type or number of such supports. The present invention is, however, concerned with maintaining the pulp distribution on the wire substantially uniform throughout the width of the wire, notwithstanding localized warping of the nozzle blade 8 by means of rods 10 to vary relative flow.

According to the present invention, a lip is fixed to the forward margin 16 of the nozzle blade 8 throughout the length of the nozzle blade. The lip 15 of FIG. 1 is prefabricated and attached to the margin 16 of the blade 8 by means of solder at 17, or otherwise. The corresponding lip shown in FIG. 2 is made integrally of the material of blade 8 by bending the material on a brake or the like to form a cross section generally comparable to that of the lip 15 and hereinafter described more particularly. The lip 151 shown in FIGS. 3 and 4 is prefabricated and clamped to the margin 16 of blade 8 and likewise provides substantially the same contour and cross section.

In all three of these constructions, the lip has a horizontal extent which is at least approximately similar to its vertical extent, being thereby sharply differentiated from a mere flange. The contour of the wetted surface of the lip inside the nozzle is most important. With the lip of the form indicated, the relative change in contour resulting from warpage of the blade and lip has a minimum effect on uniformity of distribution.

While the lip is preferably triangular or substantially triangular in cross section, it is preferred that it have a slight flat surface rather than a linear margin in adjustably spaced relation to the apron to define the orifice. So far as uniformity of coefficient of discharge at different spacings is concerned, it makes no difference whether the edge which confronts the apron is an angle or a flat. However, the angular edge is subject to wire drawing and to mechanical injury. The slightest scoring of such a corner will change the coefiicient and thereby destroy the major objectives of the invention. Accordingly, it is preferred that the corner be blunted at least slightly so that the surface which coa'cts with the apron to define the nozzle opening is not an angle. It is not necessary that it be planiform, but a flat surface at 32 is easy to machine and can readily be made with accuracy.

The surface 29 which is exposed in the path of flow is nearly vertical, but may have some inclination in the direction of flow so as to be self-cleaning. The surface 34 should flare to provide a progressively increasing cross section beyond the nozzle opening, but the precise angle is not important.

The lip should be sufficiently flexible so that it will warp with the nozzle blade 8. It may be made of various materials, stainless steel being preferred because of its freedom from corrosion.

The surface 32 which cooperates with the apron to define the nozzle opening is in general parallelism with the apron but may have a slight positive or negative angle with respect thereto according to the position of the nozzle blade 8. Since the size of the lip is exaggerated in FIG. 3, it may be noted that in practice, the width of the surface 32 is usually only about of an inch. The fiat is made by machining off the bar which constitutes the lip 15 in FIG. 1 or the lip 151 in FIG. 3 or the folded sheet metal structure which constitutes the lip 150 in FIG. 2.

When the lip is prefabricated for clamping to the free margin 16 of a nozzle blade 8 in the manner shown in FIGS. 3 and 4, the bar portion constituting the lip proper may be provided integrally with mounting means channeled at 20 to receive the free margin 16 of the blade 8 and provided with setscrews 19 for engaging the free margin 16 of the blade. Ordinarily there will be sutficient flexibility in a bar having this increased depth so that there will be no problem about warping the bar along with the margin of the blade whenever flow control is effected by means of the adjustable rods 10. However, it is contemplated that the mounting portion of the bar may be subdivided into multiple blocks 17 by means of transverse kerfs 18 as clearly shown in FIGS. 3 and 4 to provide increased flexibility. The angle and position of the bottom 36 of the kerf are completely unimportant so long as adequate seal is provided at 27 between the lip 151 and the under surface of the blade.

By way of example, and not by way of limitation, figures relating-to actual practice in a particular installation will be given. In this installation, the overall height of the lip and attaching blocks shown in FIGS. 3 and 4 was 1%; inch and the overall width was /4 inch. The face 29 was inch in height and the'face 32 was inch in width.

The face 29 deviated from right angles to the under surface 26 of the blade 8 by an angle 28 of about 15, and the angle 35 between the plane of the flat 32 and the face 34 was approximately 20.

If the installation is even approximately in accordance with the proportions above described and those illustrated in the various views of the drawings submitted herewith, the lip will very substantially reduce the nozzle discharge coefiicient, and the resulting nozzle discharge coeflicient will remain substantially constant across the width of the nozzle, notwithstanding localized war-page of the blade margin and lip for local control purposes. This will yield uniformity in distribution of the pulp on the Fourdrinier wire, notwithstanding such localized control.

I claim:

1. In a paper making machine having a stock discharge nozzle defined by an apron and a flexible blade having means for localized warpage thereof, the combination with such a blade and apron, of a lip of generally triangular form in cross section and connected with the blade margin to partake of the warpage thereof and projecting across the path of stock delivered over the apron, said lip having an inner face lying in a plane nearly normal to the apron and deviating therefrom by a slight inclination downwardly in the direction of stock discharge, said lip having a lower face in a plane at an acute angle to the apron and deviating away from the apron in the direction of stock flow, said lip having overall width in the direction of flow approximating its projection from the blade across flow whereby to maintain the distribution of stock discharged from the nozzle approximately at a constant value, notwithstanding localized variation in spacing between the lip and apron.

2. The combination set forth in claim 1 in which said lip has the lower apex of its generally triangular contour blunt, whereby it presents a non-angular surface toward said apron.

3. The combination set forth in claim 2 in which said non-angular surface comprises a narrow flat surface approximately parallel to the apron.

4. The combination set forth in claim 1 in which said lip comprises an integral portion of said blade.

5. The combination set forth in claim 1 in which said lip comprises a prefabricated bar fastened to said blade to lie beneath the lower surface thereof.

6. The combination set forth in claim 5 in which said bar has integral attaching portions extending about the margin of the blade and provided at intervals with clamping means engaging the upper surface of the blade.

7. The combination set forth in claim 6 in which the said attaching portion is provided with transverse kerfs subdividing it into separate blocks to facilitate the flexing of said bar with the margin of the blade to which it is clamped.

References Cited in the file of this patent UNITED STATES PATENTS 1,497,403 Bruner June 10, 1924 1,563,095 Lewthwaite 1 Nov. 24, 1925 1,727,928 Berry 1 Sept. 10, 1929 1,809,937 Hilsheirner m. June 16, 1931 1,818,267 Niks Aug. 11, 1931 1,846,406 Sweeney a..- Feb. 23, 1932 2,022,298 Neilson Nov. 26, 1935 2,521,261 Smith et a1 Sept. 5, 1950 FOREIGN PATENTS 64,098 Sweden Dec. 19, 1922 

